Field of the Invention
This invention relates to the insulation of structures and more particularly, to ceiling, floor and wall insulation configurations which incorporate at least one water vapor-permeable film or membrane covering, and/or located between layers of stranded fibrous, non-solid insulation, such as fiberglass insulation, which film substantially prevents the circulation or infiltration of air through the isolated insulation layers. The invention further relates to a method for increasing the efficiency of insulation in selected insulation configurations by covering, and/or inserting one or more sheets of water vapor-permeable film in particulate, batt or rolled insulation, to define boundaries for discrete layers or cells of insulation. The insulation configuration improvement and method of improving efficiency of this invention is characterized in one embodiment by one or more relatively thin, moisture-permeable films or membranes, substantially encapsulating, and/or situated between adjacent layers of insulation, which insulation configuration is supported by the ceiling structure between the ceiling joints of an attic, in walls between studs, or between other supporting members in floors, where the structure is not constructed on a slab, in order to substantially prevent air from circulating through or infiltrating the insulation. Such insulation configurations are typically characterized by a quantity of particulate or "blown" insulation, batts of selected size and rolled sheets of insulation, each of which are provided with one or more sheets or coverings of a selected barrier material which is capable of preventing, or at least minimizing air infiltration or circulation, but will allow migration of water molecules through the insulation configuration. In a preferred embodiment of the invention sheets of 2 mil polyethylene plastic membrane or film are placed over and between layers or sheets of insulation material provided in the form of batts or particulate, blown insulation which is located on the ceiling sheet rock and between the ceiling joists of an attic, or between studs in a wall or between floor joists, in order to isolate the insulation from air which normally circulates through the attic and may infiltrate and circulate in the walls and beneath the floor. In a most preferred embodiment of the invention, the membranes cover and are positioned between successive layers of particulate insulation, either by alternately installing parallel sheets of membrane in the wall area, and then blowing the insulation into the resulting open cavities or blowing the insulation into the areas between ceiling or floor joists and stapling a sheet of film between the joists to isolate the insulation from air currents. In this manner, air which circulates through the attic, walls or beneath the floor is not permitted to easily infiltrate and circulate in all layers of the insulation to provide a conduit for heat movement from the attic of the structure to the interior thereof and from the interior into the attic, or through the walls or floor, as the case may be.
Conventional insulating techniques have taken the form of placing batts, rolled or blown, loose-fill insulation between the ceiling joists of an attic, the floor joists in a floor not constructed on a slab and in the walls of a structure, in order to provide a medium which contains air pockets designed to minimize the passage of heat from the attic into the interior of the structure and from the interior back into the attic, as well as through the walls and floors of the structure. The efficiency of such insulation is commonly measured in terms of an "R" factor, which depends upon the character and thickness of the insulation. Conventional attic insulation installation frequently includes the use of a "vapor barrier" sheeting positioned between the insulation and the drywall or sheetrock or alternative ceiling covering which separates the rooms of the structure from the attic itself and serves to retard the flow of water vapor and as a support for the insulation. The vapor barrier also serves as an insulating component. An insulation material such as fiberglass or other material capable of trapping air is placed on the sheetrock and between the ceiling joists in the form of batts, rolled strips or in particulate form, by way of blowing, and the structure is considered to be well insulated, depending upon the thickness and character of the insulation installed. An appropriate "R" value is assigned the insulation, based on tests conducted under controlled conditions in the laboratory. It has surprisingly been found that insulation installed in this manner has little effect upon the heat loss and gain of a structure, especially through the attic area under a variety of weather conditions and temperatures. Experiments have shown that use of a "vapor barrier" installed in the conventional manner described above does little to aid the insulation process, since air circulation in the attic also infiltrates and circulates through the insulation and destroys much of the efficiency of the insulation due to heat transfer by convection. In many cases, the sheetrock ceiling itself is the only effective insulating barrier between the interior of the structure and the attic.
It has also been determined that the use of one or more membranes or films of selected thickness and character installed at spaced intervals in and around the insulation does not, as widely believed, trap and retain excessive quantities of moisture between the membrane layers and the insulation to degrade the sheetrock or damage structural members. In contrast, it has been found that the moisture is able to readily move through the insulation and through the certain moisture-permeable films and membranes and escape into the attic itself, where the moisture is removed by ventilators, with no adverse effect on either the insulation or the underlying sheetrock or structural members. The addition of such moisture-permeable membrane or film layers to blown, rolled and batt insulation has been found to reduce heating and cooling costs by as much as 75% and represents a significant increase in the efficiency of the underlying insulation. Since it has been estimated, for example, that 80% to 90% of the heat gain or loss in a structure having an attic takes place through the attic, the insulation configuration and method of this invention as applied to the attic in the structure becomes extremely significant in energy conservation efforts. The key to such a dramatic improvement in insulation efficiency is the creation of discrete layers or pockets in the insulation material to limit air movement from one pocket to another and reduce the resulting heat transfer through the insulating layer by convection and conduction. These pockets, layers or cells are created by placing thin films of moisture vapor-permeable material such as plastic materials, including polyethylene film, (commonly sold under the "Visqueen" tradmark) and other materials which allow the migration of water vapor, such as butcher paper and like materials, around and/or in the insulation. Convection losses occur when the air infiltrates the insulation and conduction is effected through various structures, such as film, located in or around the insulation.
Data collected over the last six years using both experimental techniques on a pilot plant scale and in full size structures demonstrates that the application of one or more membranes of film layers over at least one side and extending through the insulation significantly improves the insulating properties of insulation. In an attempt to show that three inches of fiberglass insulation was equivalent to one inch of polyurethane, it was determined that the fiberglass insulation, as conventionally sold and used, has very little effect on air movement and convection heat loss in structures. It has also been determined through additional experiments that no loose-fill or fiber batt insulation will function efficiently without a membrane to stop, or at least reduce, air circulation and infiltration in the insulation. Further testing has shown that insulation applied in the attics of homes does not function as expected by home owners. All of the tests which have been conducted to data in this research project have confirmed that the heating and cooling costs in these homes could have been cut from between 50% to 75%, had a membrane such as polyethylene having a thickness of 2 mils, or 0.002 of an inch, been installed over the insulation. It has also been determined from extensive tests that moisture vapor readily passes through this polyethelene and moisture does not build up in the insulation because of this membrane.
Many efforts have been made in recent years to improve the insulating efficiency in structures, and typical of these efforts is the "Building Insulation and Method of Installation" disclosed in U.S. Pat. No. 4,155,208, to John A. Shanabarger. The insulation and method of this invention includes use of a sheet of heavy plastic and cooperating elongated plastic bags which fit between the studs of a wall structure and conform to the insulating spaces between the studs to insulate the walls. The bags are resilient, they can be expanded volumetrically to substantially fully occupy the spaces between the studs and the bags can be attached to the studs by stapling, or by other techniques. U.S. Pat. No. 3,298,150, to D.E. Ahlquist, discloses "Wall Insulation Structures and Method of Using Same", and describes insulation for walls and other surfaces which are characterized by multiple blocks of insulating material contained in an envelope having side panels which are disposed along the walls to insulate the walls. Another insulating wall structure is disclosed in U.S. Pat. No. 3,641,724, to James Palmer, which structure includes an integral box construction built directly into a selected wall section and further includes interior foam materials such as various urethanes, to provide the necessary insulation. An "Insulated Roof" is disclosed in U.S. Pat. No. 4,147,003, to Robert J. Alderman, which roof includes a reel of flexible sheet material mounted on a support frame and situated over a space between adjacent roof purlins. This framework is moved along the purlins and the sheet material is progressively unrolled, formed and guided by the framework down into the space between the purlins. Insulation material is placed in the trough on top of the sheet material in order to insulate the roof. Another, insulated roof structure is disclosed in U.S. Pat. No. 4,047,346, also to Robert J. Alderman, which includes a reel of wire mesh and a cooperating reel of sheet material carried by a supporting framework to faciliate progressively unrolling the layers of wire mesh and sheet material for application to the spaces between the roof and purlins. Insulation is then placed in the wire and sheet material trough, in order to insulate the roof.
It is an object of this invention to provide in one embodiment, new and improved insulation configurations for insulating the attics, walls and floors of homes, offices, and other structures, which insulation configurations are each characterized by one or more moisture-permeable film or membrane layers covering and/or placed between layers of insulation resting on the ceiling in the attics, between studs or other wall supports and between floor joists, which film or films isolate the insulation into layers or cells and serve to minimize air infiltration and circulation through the insulation, to increase the insulating efficiency.
Another object of this invention is to provide an improvement to existing insulation in an insulated attic having a layer of sheetrock attached to the bottom of supporting attic ceiling joists and a mass of insulation located between the ceiling joists and supported by the sheetrock, which improvement includes placing a moisture vapor-permeable film or membrane of selected thickness over the insulation and adding additional layer of insulation, with another film extending over the second layer of insulation, in order to minimize the infiltration of air through the insulation layers and thereby improve the efficiency of the insulation.
A still further object of the invention is to provide improved insulation configurations for attics, floors having floor joists and walls, which configurations include at least one water vapor-permeable plastic membrane or film of selected thickness covering and/or installed in a quantity of insulation located on sheetrock between the ceiling joists of the attic, between floor joists, or between studs in a wall, which membrane or membranes serve to isolate discrete layers of insulation and substantially prevent air from circulating through the isolated layers and increases the efficiency of the insulation, while allowing moisture to migrate through the isolated insulation layers without collecting therein and damaging the insualtion, the underlying sheetrock or any structural members.
Still another object of this invention is to provide a method for increasing the efficiency of insulation in the attics, floors and walls of structures, which method includes the expedient of placing one or more layers of water vapor-permeable membrane or film in and over the insulation, in order to create boundary surfaces and isolate discrete layers of insulation to prevent extensive infiltration and circulation of air through the isolated layers or cells of insulation.
A still further object of the invention is to provide a method for minimizing the circulation of air and heat through insulation installed in the attics, walls and floors of strucures, which method includes installing at least on moisture-permeable, plastic membrane or film over and/or in the insulation, in order to substantially isolate multiple layers or cells of insulation and increase the efficiency of the insulation.